Coordinated Boom Lift and Carriage Transfer

Abstract

A telescopic boom materials handling vehicle includes a vehicle chassis and a transfer carriage supported by the chassis and configured for longitudinal displacement relative to the chassis between the retracted position and an extended position. A telescopic boom is pivotably affixed at a first end to the transfer carriage. A control system controls operation of the telescopic boom to maintain a height of the load supported by the telescopic boom during longitudinal displacement by the transfer carriage, regardless of a terrain slope on which the vehicle chassis is supported.

1 . A telescopic boom materials handling vehicle comprising:
 a vehicle chassis including a chassis angle sensor, the chassis angle sensor detecting an attitude of the chassis relative to true horizontal;   a transfer carriage supported by the chassis, the transfer carriage configured for longitudinal displacement between a retracted position and an extended position, wherein the transfer carriage includes a length sensor that monitors a position of the transfer carriage relative to the chassis;   a telescopic boom pivotably affixed at a first end to the transfer carriage and including a boom angle sensor, the boom angle sensor detecting an angle of the boom relative to the chassis; and   a control system communicating with the chassis angle sensor, the length sensor and the boom angle sensor and controlling operation of the telescopic boom according to signals from the chassis angle sensor including the attitude of the chassis relative to true horizontal, the length sensor including the position of the transfer carriage relative to the chassis, and the boom angle sensor including the angle of the boom relative to the chassis.   
   
   
       2 . A telescopic boom materials handling vehicle according to  claim 1 , wherein the telescopic boom comprises a load support apparatus at a second end thereof, the load support apparatus supporting a load for displacement by the telescopic boom materials handling vehicle. 
   
   
       3 . A telescopic boom materials handling vehicle according to  claim 2 , wherein the control system is configured to control operation of the telescopic boom based on the signals from the chassis angle sensor, the length sensor and the boom angle sensor to maintain the load support apparatus level during longitudinal displacement by the transfer carriage, regardless of a terrain slope on which the vehicle chassis is supported. 
   
   
       4 . A telescopic boom materials handling vehicle according to  claim 1 , wherein the chassis angle sensor is a gravity sensor. 
   
   
       5 . A method of maintaining a load supported on a telescopic boom materials handling vehicle level regardless of a terrain slope on which the vehicle is supported, the vehicle including a vehicle chassis including a chassis angle sensor, a transfer carriage including a length sensor, and a telescopic boom including a boom angle sensor, the method comprising:
 detecting with the chassis angle sensor an attitude of the chassis relative to true horizontal;   monitoring with the length sensor a position of the transfer carriage relative to the chassis;   detecting with the boom angle sensor an angle of the boom relative to the chassis; and   controlling operation of the telescopic boom according to the attitude of the chassis relative to true horizontal, the position of the transfer carriage relative to the chassis, and the angle of the boom relative to the chassis.   
   
   
       6 . A method according to  claim 5 , wherein the controlling step is practiced to maintain a height of the load at an initial lift height selected by an operator. 
   
   
       7 . A method according to  claim 6 , wherein the controlling step is further practiced by operating the boom to maintain the height of the load when the transfer carriage is displaced relative to the vehicle chassis. 
   
   
       8 . A method according to  claim 5 , wherein the telescopic boom comprises a load support apparatus at an end thereof opposite from the vehicle chassis, the load support apparatus supporting the load, and wherein the method further comprises maintaining an attitude of the load support apparatus regardless of the terrain slope on which the vehicle is supported and regardless of a position of the telescopic boom based on an operator-selected position. 
   
   
       9 . A telescopic boom materials handling vehicle comprising:
 a vehicle chassis;   a transfer carriage supported by the chassis, the transfer carriage configured for longitudinal displacement relative to the chassis between a retracted position and an extended position;   a telescopic boom pivotably affixed at a first end to the transfer carriage; and   a control system controlling operation of the telescopic boom to maintain a height of a load supported by the telescopic boom during longitudinal displacement by the transfer carriage, regardless of a terrain slope on which the vehicle chassis is supported.   
   
   
       10 . A telescopic boom materials handling vehicle according to  claim 9 , further comprising a chassis angle sensor that detects an attitude of the chassis relative to true horizontal, a length sensor that monitors a position of the transfer carriage relative to the chassis, and a boom angle sensor that detects an angle of the boom relative to the chassis, wherein the a control system controls operation of the telescopic boom based on output from the chassis angle sensor, the length sensor and the boom angle sensor.